This is more common than you think. So long as you know what you want as an outcome, don't overthink it. Unless you're working with higher-than-average levels of sociopathy, you'll find that you can talk about it and transition to something you find more rewarding.

Also try not to frame it as something shameful/step-down. Individual Contributors and Management are entirely different jobs - clearest evidence of that is what your calendar and day-to-day look like. There's some overlap, but it's a pivot, and that's okay.

(P.S. Stick with the personal trainer and running group :)

Good luck.